ps2kbd.pio

.program ps2kbd

.wrap_target
  wait 0 pin 1 ; Start Bit
  wait 1 pin 1
  set x, 8
again:
  wait 0 pin 1 ; Data Bits + Parity Bit
  in pins, 1
  wait 1 pin 1
  jmp x-- again
  wait 0 pin 1 ; Stop Bit
  wait 1 pin 1
  irq wait 0
.wrap

% c-sdk {
static inline void ps2kbd_program_init(PIO pio, uint sm, uint offset)
{
  pio_sm_config c = ps2kbd_program_get_default_config(offset);
  sm_config_set_in_shift(&c, true, true, 9); /* 8 Data Bits + Parity Bit */
  sm_config_set_fifo_join(&c, PIO_FIFO_JOIN_RX);

  /* Configure pins 4 (Data) and 5 (Clock) as input. */
  sm_config_set_in_pins(&c, 4);
  pio_gpio_init(pio, 4);
  pio_gpio_init(pio, 5);
  pio_sm_set_consecutive_pindirs(pio, sm, 4, 2, false);

  gpio_pull_up(4);
  gpio_pull_up(5);

  pio_sm_init(pio, sm, offset, &c);
  pio_sm_set_enabled(pio, sm, true);
}
%}